1. Field of the Invention
The present invention generally relates to a wireless communications system, and more particularly to a wireless terminal device, an indoor base station apparatus, and a control apparatus.
2. Description of the Related Art
An emergency alert location notification is a function for transmitting information regarding a location from which an emergency alert is transmitted to an emergency alert receiving institution in a case where the emergency is alerted to the police department (Phone No. 110), the fire department (Phone No. 119), or the coast guard (Phone No. 118) by a mobile telephone.
In a case where there is an emergency alert, a mobile communications carrier must gather location information from a party transmitting the emergency alert and provide the information to an emergency alert receiving institution such as the police department, the coast guard, and the fire department. This emergency alert location notification has been obligated in Japan from April of 2007.
In order to obtain location information from the transmitting party, location information obtained from a GPS (Global Positioning System) or information of the location where a base station apparatus is positioned are used. In a case where a mobile phone is located in an environment capable of receiving GPS signals, the reception of GPS signals by the mobile phone allows the mobile communications carrier to identify the location of the mobile phone and provide information of the identified location to the emergency alert receiving institution.
In providing location information during an emergency in other countries, the United States, for example, provides location information according to E911 (Enhanced 911). In the United States, it is obligatory to provide information identifying the location of a transmitting party to a Public Safety Answering Point (PSAP) which is an institution for receiving 911 calls.
In recent years, femtocell has been considered to be used for providing mobile phone service areas. Femtocell is a communications area (cell) that is covered by a very small base station apparatus with extremely small output. The femtocell covers an area with, for example, a radius of approximately several tens of meters. In the femtocell, a base station apparatus may also be referred to as an indoor small base station. In the femtocell, a Femtocell Gateway (FGW) which is a femto dedicated gateway installed by a mobile phone communications carrier and a femtocell Access Point (femtoAP) which is a femtocell dedicated small indoor base station are connected by using an IP broadband line. For example, the IP broadband line may be Asymmetric Digital Subscriber Line (ADSL) or Fiber To The Home (FTTH). The femtocell can provide a better radiowave reception environment than a macrocell. Further, the femtocell can provide a high speed data communications environment. Further, the femtocell can allow a specific user to exclusively use a frequency, to thereby improve frequency usage efficiency. Various services using femtocell (hereinafter also referred to as femtocell service) are being considered by mobile phone communications carriers. The femtocell service includes, for example, a fixed-fee service.
The femtocell service can easily be obtained in an environment where IP broadband lines are installed. For example, by connecting an IP broadband line to a femtocell dedicated small indoor base station, the femtocell service can easily be obtained. Further, the femtocell dedicated small indoor base station can be installed in a user's residence receiving the femtocell service. This alleviates management constraints of mobile phone communications carriers. For example, the user may be able to freely change the location of the small indoor base station. In another example, the user may be able to freely turn the power of the small indoor base station on and off.
Since the user can freely move the location of the small indoor base station, managing the location of the small indoor base station may be a problem for the mobile phone communications carrier.
For example, a user purchases or borrows a small indoor base station from a mobile phone communications carrier. Then, the user installs the small indoor base station. The user may then change the installment location of the small indoor base station. For example, the location of the installment location may be changed in a case where the user moves to another residence. In this case, the method of managing the location of the small indoor base station may become a problem for the mobile phone communications carrier.
As described above, the mobile communications carrier identifies the location of a mobile phone receiving GPS signals and provides information of the identified location of the mobile phone to an emergency alert institution. Further, the mobile communications carrier may also provide location information of a fixed base station apparatus communicating with the mobile phone to the emergency alert institution.
A case where a user is located in an environment capable of receiving a femtocell service is described below. That is, in this case, a location of a mobile phone is registered in a service area provided by radiowaves transmitted from a small indoor base station. In a case where an emergency alert is sent where a mobile phone is in an environment capable of receiving GPS signals, the location identified by GPS signals can be reported to the mobile phone communications carrier. However, a problem occurs when the mobile phone is in an environment unable to receive GPS signals as described below.
In a case where a mobile phone is in an environment unable to receive GPS signals, the mobile phone communications carrier provides location information of a visited cell when a radiowave is transmitted by the mobile phone. In the field of mobile phone services, a cell is commonly understood as an area in which radiowaves are transmitted from a base station apparatus. Further, mobile phone communications carriers are required to manage location information of base station apparatuses. However, as described above, small indoor base stations are expected to have their locations changed by the user. Further, the small indoor base stations are also expected to be used in an environment where absolutely no outside radiowaves can reach. Therefore, in a case of emergency, the small indoor base station itself is to identify its location so that location information of the mobile phone can be provided to the emergency receiving institution.
However, there may be a case where the small indoor base station is in an environment unable to receive not only GPS signals but also radiowaves from a macro-cell neighboring the area at which the small indoor base station can receive radiowaves. The macro-cell is an outside cell capable of covering a radius of 1 km. In such a case, it is difficult for a mobile communications carrier to manage, for example, information of the neighboring cell along with location information of the small indoor base station.
In a case where an emergency alert is transmitted from a mobile phone located within a cell of the small indoor base station situated in such an environment, the mobile communications carrier cannot identify the location of the small indoor base station. Thus, the mobile communications carrier cannot provide location information to an emergency receiving institution. This adversely affects emergency operations.